This invention pertains to a method of repairing furnace, kiln or oven, and particularly relates to a method of repairing injured portion of refractory furnace-lining. (Hereinafter, in the specification and claims, furnace, kiln and oven are referred to collectively as "furnace". ).
Heretofore, there has been used a method of repairing a furnace which comprises cutting off after cooling the surface the injured portion of refractory furnace-lining by means of "chipping work by hand" using a chisel or machine drill to make a drilled hollow, and filling the hollow with a refractory material. This method, however, has a fault that the time and labor required for accomplishing the work are tremendous with the resultant work-efficiency being quite low. Furthermore, when the chipping work is carried out, numerous cracks are caused in the lining by the action of striking the chisel or drill. On account of this cracking, the remaining portion of the lining frequently can not be depended upon for secure use.
There is another prior method which does not include cutting off the injured portion of the refractory furnace-lining. This method comprises spraying a slurry of refractory material over said injured portion to fill the hole caused by the injury, followed by finishing up by means of shoveling or patching step. This method, however, has a fault that the adhered refractory material is liable to peel off from the substrate. Furthermore, when the spraying work is carried out, there is a big rebound loss of the slurry, resulting in an uneconomical consumption of the refractory material.
The present inventors made an attempt to remove the faults mentioned above, using an acetylene burner or oxyhydrogen burner for a general metal-working. Specifically, these burners were used to cut off the injured portion of refractory lining, and then a rigid refractory lining block shaped to conform to the cut-hole was inserted thereinto, followed by welding the periphery of said block to the contact surface of the cut-hole using the same burner as mentioned above. It was found, however, that the temperature of the burner flame was too low to effect a satisfactory cutting off of the injured portion of the lining. Further, the burner was quite unable to carry out the welding.